Development of Multi-tiered Wetland Assessment Methods for Monitoring Wetland Condition

Amy Deller JacobsDE Department of Natural Resources and

Environmental Control

Delaware Wetland Status and Trends

• 54% lost since 1780’s

• Most of loss due to ditching and channelization and

direct conversion to ag of nontidal wetlands

•From 1986-1997 there was an 80% reduction in loss from previous decade•From 1982-1992

Delaware lost 2000 acres

Delaware Wetland Status and Trends

Why Monitor Condition?• Evaluate what functions are being performed and at what level

• Determine stressors

• Gain information to guide restoration and enhancement

• Meet requirements of TMDL lawsuit/ Required under Clean Water Act

LEVEL 1GIS PlatformNo Fieldwork

LEVEL 2Rapid AssessmentSome Fieldwork

LEVEL 3Intensive Field Sampling

Level of Effort IncreasesLe

vel o

f Det

ail D

ecre

ases

Multiple Levels of Assessment

Nanticoke Wetland Study

10,000Meters

EMAP sample points

Overall Success RatePermission for Access

N = 446

45%

17%

Granted

No Contact

Denied

38%

No Contact

Granted

Denied

38%44%

18%

N = 321

TNC STATE

020406080100

Yes No

Success Rate with ContactExcluding Public Lands

N = 227

Perc

ent 67%

33%

Hydrogeomorphic Models

Data

Variable Variable VariableVariableVariable

Function Function

HGM Function Wildlife Habitat(Vdisturb + ((Vtba + Vtden)/2) + Vshrub + Vsnag)/4

Results are between 0 and 1

Total EffortTotal Effort6%

2%

2%

6%65%

1%3% 2%

13%

Printing of Map

Reviewing Map/ enter indatabaseLooking up landownerinformationEnter in database andSend letterFollow-up phone call

Initial Site Visit

Field Crew Preparation tosampleSampling Site

Sending Thank you letterupdating database24 man-hours

Rapid Assessment (Level II)Development of a Rapid Assessment Method• Evaluates condition and can distinguish

various levels • Requires a site visit• No detailed data collected

• Based on HGM models and field experience• Evaluates stressors present at a site• Weights stressors according to their impact

on 4 categories (hydrology, habitat, biogeo cycling, and landscape)

• Provides one overall score of the condition of the wetland

Rapid Assessment (Level II)

Mowing -3

Farmed -9

Grazing -3

Forest harvesting (>50% of stand)

Recovered 0

Recovering -5

Recent -7

Cleared not recovering -7

Excessive herbivory

Presense of invasive spp.

Dominate the site -7

Do NOT dominate the site -2

Chemical defoliation -3

Managed or converted to pine -5

Burned -3

Trails -1

Garbage/ isolated dumping -1

Other

Subtotal Habitat Community 10 + sum of above, if score <0 record 0

Habitat Category

Rapid Assessment (Level II)

Total Score

(Hydrology/10) + (Hydrology/10)*(Biogeo/10)) + (Habitat/10) + ((Habitat/10)*(Landscape/10))

Current projects• Validating with HGM (level III)• Determining sensitivity of methods• Evaluating transferability to other areas of

the state

Rapid Assessment (Level II)

Comparison of Effort to sample 50 sites

• 4 hours/ site• 4 person crew• 25 days(2 sites/day)• 100 person-days• Several hours office

work

• 2 hours/ site• 2 person crew• 12.5 days (4 sites/ day)• 25 person-days• Minimal office work

Level III Level II

LEVEL 1GIS PlatformNo Fieldwork

LEVEL 2Rapid AssessmentSome Fieldwork

LEVEL 3Intensive Field Sampling

Level of Effort IncreasesLe

vel o

f Det

ail D

ecre

ases

Multiple Levels of Assessment

Landscape Level Assessment (I)

• Inventory – status and trends• Updated wetland maps

– Including HGM modifiers – Provide additional information

• Landscape analysis– Inferring condition based on indicators in

surrounding landscape

Stepwise multiple regression results for flat HGM functions

Variables

Function No. Names r2 *

Biogeochemistry 5 ex100 –ex500 –FOREVER100 –GRASS1000 FOREST1000

0.44

Habitat 5 +nat100 –nimpound1000 –FOREVER 100 –GRASS1000 FOREST1000

0.35

Hydrology 3 -ex100 –nat1000 +FORDEC1000 0.43

Plant 2 -ex1000 +FORDEC100 0.17

*n=89, p<0.0001 for all models

Stepwise multiple regression results for riverine HGM functions

Variables

Function No. Names r2 *

Biogeochemistry 3 -ex100 +nat1000 –DEVTOT100 0.51

Habitat 2 -ex100 +nat1000 0.42

Hydrology 5 -ex100 +nat1000 +FOREST100 +FOREST1000 -FORDEC1000

0.70

Landscape 6 -ex100 –ex1000 +nat1000 –CROP100 –DEVTOT1000 +FOREVER1000

0.70

Plant 2 -ex500 –DEVTOT100 0.31*n=54, p<0.0001 for all models

Assess loss and

condition by subclass

Determine Spatial Need to

Restore Function

Prioritize Restoration and

Protection Projects

Monitor to Determine Progress and Reassess Priorities

Determine Stressors